Compositions comprising ethylene-vinyl acetate copolymer,fatty acid salt and fatty acid amide



United States Patent C CUMPOSITIDNS COMPRISING ETHYLENE-VINYL ACETATECOPOLYMER, FATTY ACID SALT AND FATTY ACID AMlDE Lee R. Ridgeway,Cincinnati, Ohio, and Joseph Fischer,

Urbana, llll., assignors to National Distillers and ChemicalCorporation, New York, N.Y., a corporation of Virginia No Drawing. FiledJan. 19, 1966, Ser. No. 521,538

lint. Cl. C08f 45/00, 37/04 US. Cl. 260-23 Claims ABSTRACT OF THEDISCLOSURE A polyolefin composition including in combination anethylene-vinyl acetate copolymer, a metal salt of a fatty acid and anamide of a fatty acid.

This invention relates to polyolefin compositions having improved slipand non-blocking properties. More particularly, the invention relates toethylene/vinyl acetate copolymer compositions Whose normally highfilm-to-film coefficient of friction is reduced by incorporating intosaid composition a metal salt of a fatty acid in combination with atleast one fatty acid amide.

The use of low density polyethylene for film applications necessitatedthe development of improvements in certain characteristics of the film.In order to permit the use of polyethylene films on high speed bagmaking and I other machinery, it was necessary to develop films withimproved slip characteristics, that is, the ability of the film to slidesmoothly and quickly over metal or other surfaces or over another layerof film. In addition, additives were used to prevent blocking, that is,the tendency of film to cling to itself on the roll and thus to resistseparation by any peeling force. A suitable slip agant or combination ofslip and anti-block agents in polyolefins will impart a controlled anddesired level of slip to the film and will not impair the opticalproperties of the product.

The blocking and slip tendencies of polyolefin films have been improvedby the incorporation into the resin of various fatty acid amides, suchas oleamides, stearamides, and so forth.

The use of materials known to be effective mold release agents, e.g.,metallic stearates, has not been feasible in the polyethylene filmindustry because of the limited compatibility of the polymer withforeign substances. Excessive plate-out on the surface of dies and rollsin fabricating equipment and the heavy surface layer of such deposits onthe film are undesirable.

Inorganic silica compounds have been tried as antiblocking agents withsome degree of success; if, however, large amounts of the compound areused or if the particle size is too large, the haze of the polymer filmis increased.

Because of their inherent flexibility and elastomeric properties,ethylene/vinyl acetate copolymers present greater problems thanpolyethylene in producing films with adequate slip characteristics. Manycopolymers of ethylene and vinyl acetate will produce films withexcellent clarity, toughness, low temperature properties, and otherdesirable characteristics, but with a very strong tendency towardblocking. If the commonly used and accepted polyethylene slip andanti-block agents, e.g., oleamides or stearamides are incorporated intothe ethylene/ vinyl acetate copolymer in the concentrations normallyused, these additives are not effective. If it is attempted to remedythis by greatly increasing the amount of fatty acid amide, the producttends to have a greasy feel and to exhibit undesirable wet blocking. Inaddition, the or- Patented Oct. 21, 1969 'ice ganic amides alone do notappear to impart sufiicient anti-block properties to the copolymerfilms. If high concentrations of inorganic anti-block agents are used,the product becomes very hazy and loses the desirable transparency andoptical sparkle desirable for many applicatrons.

It has thus not been found possible to improve the slip and anti-blockproperties of an ethylene/ vinyl acetate copolymer film Withoutimpairing its other desirable properties by taking the best of the slipor anti-block compositions now used with polyethylene or by eitherincreasing or decreasing the constituents of the additive composrtlons.

It is, therefore, an object of this present invention to provide anethylene/vinyl acetate copolymer resin film composition having improvedslip and anti-block characterrstics.

An additional object is to provide an ethylene/vinyl acetate copolymercomposition wherein film made therefrom has improved slip andanti-blocking characteristics and wherein other physical properties ofthe film, such as clarity, permeability, scalability, printability, andthe like, are substantially unaffected.

A further object of this invention is to provide ethylene/ vinyl acetatecopolymer resins that can be converted into films by standard processingtechniques, such as are used to make tubular or cast film, and to impartthereto a balance of slip and anti-block characteristics withoutimpairing other desirable characteristics, such as optical properties.

Other objects will become apparent from the following detaileddescription.

In accordance with this invention, plastic compositions, particularlysolid copolymers of ethylene and vinyl acetate, are given improved slipand anti-blocking properties by incorporating into such compositions asmall amount, based upon the Weight of said plastic compositions, of ametal salt, of a fatty acid in combination with a fatty acid amide.

The amounts of metal salt and fatty acid amide used may be varied over awide range, depending upon the desired improvement in slip andanti-block properties. In general about 0.01 to about 4 percent of themetal salt plus about 0.1 to about 0.8 percent of the fatty acid amide,based on the weight of the polyolefin composition, will givesatisfactory results. Preferably about 1.0 to 2.0 percent of the metalsalt and about 0.1 to 0.2 percent of the fatty acid amide are used. Ifdesired, however, less than 0.1 and more than 4 percent of the metalsalt and less than 0.1 and more than 0.8 percent of the fatty acid amidecan be used Without deleterious results. The optimum quantity of themetal salt depends upon the amount of vinyl acetate in the copolymerbeing treated.

The improved compositions embodied herein can be prepared by any ofseveral suitable methods known in the art for providing a uniformmixture of a plastic and additive materials to impart a desiredproperty. Such methods include the addition of the stated amides andmetal salts as a solid, in solution in inert solvent, or as a slurry ina non-solvent to the plastic in either dry fluff or molding powder form,followed by drying and tumbling. The stated amide and salt additives canalso be incorporated into the plastic by melt blending the ingredientsin conventional apparatus, such as a Banbury mixer, heated rolls, etc.The salt and the amide can be added to the plastic compositionseparately, or they can be premixed and the mixture of metal salt andamide added to the plastic composition.

Suitable metal salts are those of fatty acids having from about 12 toabout 22 C atoms, such as for example zinc, calcium, aluminum,magnesium, and lithium laurate; zinc, calcium, aluminum, magnesium, andlithium behenate; zinc, aluminum, magnesium, dibasic lead, cerium, andcalcium stearate; zinc palmitate; and combinations thereof. Fatty acidamides that give good re- 4 is defined as follows: 10 feet is divided bythe thickness of the film in mils. This length is allowed to hang freeas the roll is unwound. If the weight of this free-hanging material ismore than enough to unroll the film, the roll openability is greaterthan 50 percent. If not, the roll sults when combined with the metalsalts are the amides 5 openability is less than 50 percent. In thistest, a roll of fatty acids having from about 12 to about 22 C atoms,openability of 70 percent or greater is regarded as such as, forexample, laurylamide, palmity-lamide, oleylacceptable. amide,stearylamide, linoleylamide, erucylarnide, behen- Jungle block ylamideand ji of i The jungle block openability test, is determined bv a f ;f 31511335 5 gg g gggg g glacing a small stacklof film, ugually 20 sheetsor layers.

' etween t t at least one metal salt, and at least one fatty ac1d amide.pounds gh rf i g f i g i Other conventional polyolefin film resincomponents, such at F for 24 ho'urs Samples g then removed gi g i fi ggg gg sg g g g lggggzfii 23 852 13 15 allowed to cool, and the ease ofopenability is measured. however that the added amount of theseingredients is A Juggle dblock i g f than permm ls cons: ere accepta e.1m w 1c a s open etween the msufiictient tfotglter substatntlally theslip and anti-blocking fingers when picked up is considered 0t have 100percent 2 i i fi k d t openability, whereas film which cannot be openedwhen n er 0 1 t e E e lmpioveinen 51p worked between the fingers haszero openability. properties and 1n anti-blocking properties imparted toiplastic compositions by the practice of this invention, cast E t t ottld ms were re ared from so id eth lene/vin l acetate copolymers t w liichhad been added at least cine metal salt Thls. a quahtatlve test P torate the unevenness or and at least one fatty acid amide and tested asfollows: blotchmess of the It IS generally by a Panel of three, as veryheavy, heavy, medium, slight, very slight, R011 0 enabim and none. Arating of medium is regarded as acceptable p y for most applications.The following data illustrate the This test evaluates the ease ofunrolling a roll of cast improvement in slip and anti-blockingproperties imparted film stored at room temperature and is determined asa to a film by the incorporation of at least one metal salt function ofhow the film opens or falls away from the and at least one fatty acidamide in an ethylene/vinyl roll. Zero roll openability is defined ascomplete blockacetate copolymer composition having a melt index of ing,that is, it is not possible to separate the film from 1.5 and a densityof 0.937 g./cc. Included for comparathe roll without exerting a force ortearing action. At 100 tive purposes are results of tests made on filmsprepared percent r011 openability, the film falls freely from the r froman ethylene/vinyl acetate resin plus only one of the roll as the roll isunwound. Fifty percent roll openability 3Q two additives required forthis invention.

TABLE Film Roll openability, A t thickpercent ganglia H moun ness, 0care, Additive percent mils lweek 1month percent percent Extent mottledNone 4 36 22 17 3.0 None.

Zinc stearate 2 4 73 62 22 2.3 Slight.

Aluminun stearate 2 4 53 30 23 2.0 Medium.

Polybutene/wax dispersion 1 4 28 33 27 2.3 Slight.

1lgltlfiyletie bislstearamide 0 f 4 65 62 25W 3.4 Slight.

e eny am e e gehenlylamaide 3.2 4 26 43 27 2.2 Slight.

rucy 31111 e 7 lglirfierallfillerf 4 32 25 2.6 Very slight.

6 eny 21ml Erucylamide- 0. 1

8 ginc sgearae 0 1 4 67 57 1.2 Very slight.

rucy aim e 9 Iglue stiearae 012 4 64 50 55 2.9 Medium.

ruey aml e 10 IZinesiieara(t1e 0 2 4 71 38 2.5 Slight.

rucy am e.

11 glue stiearage... 0 g 4 70 3.0 Medium.

ruey am e 12 IZgiuc stiearae 0 g 4 86 93 72 1.7 Medium.

rucy 51ml 6 13 stelarat z1 0 Z 4 76 90 63 1.9 Slightly grainy.

e eny 5.1111 e 14 galciulm st arata. 0 2 4 40 43 27 2.2 Medium.

ruey EH11 9 15 I(ialciuim stgarate 0 42 4 44 43 28 1.8 Medium grainy.

rucy arm 8 16 glnmjlnumdstearate 0 Z 4 55 42 32 2.5 Medium.

rucy aml e 17 Zinc stearate 1 4 60 60 45 2.7 Medium.

Aluminum stearate 1 Erucylamide 0. 4

Wet block.

Additional runs were made using combinations of various amounts of zinclaurate, zinc palmitate, or zinc behenate with various amounts ofoleylamide, palmitylamide, linoleylamide, or laurylamide. The resultsobtained were comparable to those in the table using zinc stearate,calcium stearate, or aluminum stearate with erucylamide or behenylamide.

From these data it can be seen that in general the use of a combinationof at least one metal salt of a fatty acid having about 12 to 22 C atomsplus at least one amide of a fatty acid having about 12 to 22 C atomsresults in a film that has both improved slip and anti-blockingproperties with no detrimental eifect on the appearance and the opticalproperties of the film. In addition to giving a product film that issuperior to one made from a copolymer resin containing no slip additive(run 1), the copolyrner resin compositions of this invention yield filmsthat are superior to those made from resin compositions containing onlya metal salt of a fatty acid (runs 2 and 3) and to those made from resincompositions containing only amides of a fatty acid (runs 4, 5, 6, and7).

While there are above disclosed but a limited number of embodiments ofthe invention herein presented, it is possible to produce still otherembodiments Without departing from the inventive concept hereindisclosed. It is desired, therefore, that only such limitations beimposed on the appended claims as are stated therein.

What is claimed is:

11. A polyolefin composition comprising an ethylene vinyl acetatecopolymer, an amount effective to improve the slip tendencies of saidcopolymer, of at least one metal salt of a saturated fatty acid havingabout 12 to 22 C atoms, and at least one amide of a fatty acid havingabout 12 to 22 C atoms.

2. The composition of claim 1 wherein the metal salt is present in anamount between 0.01 and 4 percent, based on the weight of the copolymer,and the amide of the fatty acid is present in an amount between about0.05 and 0.8 percent, based on the weight of the copolymer.

3. The composition of claim 1 wherein the metal salt is selected fromthe group consisting of zinc stearate, calcium stearate, aluminumstearate, zinc laurate, zinc palmitate, zinc behenate, and mixtures ofthese and the amide of the fatty acid is selected from the groupconsisting of erucylamide, palmitylamide linoleylamide, behenylamide,laurylamide, oleylamide, stearylamide, and mixtures of these.

4. The composition of claim 1 wherein the metal salt is present in anamount between about 1.0 and 2.0 percent, and the amide of the fattyacid is present in an amount between about 0.1 and 0.2 percent, based onthe weight of the copolymer.

5. A polyolefin composition having improved slip and anti-blockingproperties comprising an ethylene/ vinyl acetate copolymer; about 0.01to 4 percent, based on the weight of the copolymer, of at least onemetal salt of a fatty acid having about 12 to 22 C atoms selected fromthe group consisting of zinc stearate, calcium stearate, aluminumstearate, zinc laurate, zinc palmitate, zinc behenate, and mixturesthereof; and about 0.05 to 0.8 percent, based on the Weight of thecopolymer, of at least one amide of a fatty acid having about 12 to 22 Catoms selected from the group consisting of erucylarnide, linoleylamide,behenylamide, laurylamide, palmitylamide, oleylamide, stearylamide, andmixtures thereof.

References Cited UNITED STATES PATENTS 2,462,331 2/1949 Myers 260232,938,879 5/1960 Mock et al. 260-326 3,205,190 9/1965 Braus et al.26032.6 3,326,840 6/1967 Ross et al. 260-326 3,330,796 7/1967 Mock etal. 26032.6 3,362,839 1/1968 Weindel 106-270 DONALD E. CZAJA, PrimaryExaminer R. A. WHITE, Assistant Examiner U.S. Cl. X.R. 260-285, 32.6, 41

